This invention relates to fluid system seals, and more particularly to a metal-to-metal seal capable of sustaining its sealing qualities under extreme temperature and pressure conditions without fluid leakage.
The interconnection of numerous elements of fluid-carrying systems frequently involves the use of flanges to permit the elements to be bolted together to form a portion of a flow passageway of a fluid flow system. The use of resilient seals between such elements to permit fluid-tight interconnections in such fluid-carrying systems is well known. Among the more common types of resilient seal materials are cork, rubber, synthetic elastomers, and the like. Typically, resilient seals are positioned between two metallic elements forming a part of the fluid system, and in such a way as to completely surround the flow channel so that leakage does not take place.
Resilient seals, which most often are in the form of flat gaskets, O-rings, and the like, have the advantage of being able to expand and contract as the system itself expands and contracts because of temperature or pressure changes. However, most of the more common resilient seal materials either soften excessively, melt, break down, or otherwise permit leakage when subjected to high temperatures, such as temperatures over about 400.degree. F. Thus, the utility of such resilient seals is limited to the extent that they can only effectively be used under moderately high temperature conditions. Similarly, under low temperature conditions of the order of about -65.degree. F. or so, the commonly used resilient seal materials become less effective by reason of loss of resilience and flexibility. However, if suitable seals are not used and the various elements of the fluid system are merely bolted together, there is the danger of fluid leakage and of distortion of the metal elements as a consequence of expansion and contraction caused by temperature excursions. If the elements are too rigidly interconnected, the expansion and contraction stresses in the system, which build up with temperature extremes, could cause a break in the system with a consequent loss of the fluid and possible inoperability of the system. The foregoing temperature effects are magnified when high operating pressures are superimposed upon such a fluid-carrying system.
In addition to the temperature effects in existing sealing arrangements, as pressures within the fluid-carrying system increase, the pressure effects on existing seals operate to cause separation of the sealing elements, and thus the propensity for leakage increases as the pressure increases.